263 



THE SOUTHERN PLANTER. 



From the British Farmers' Magazine. 



Lecture on Agricultural Chemistry. 



B"V» MR. J. C. NESBIT. 



On Tuesday, Nov. 11, 1856, a lecture 

 on General Agricultural Chemistry was 

 delivered in the Central "Subscription 

 Rooms, Launceston, Cornwall, by J. C. 

 Nesbit, Esq., of the Agricultural and 

 Chemical College, Kennington, in fulfil- 

 ment of an engagement entered into by 

 him with the committee of the Launceston 

 Agricultural Society. 



In consequence of the lecture being de- 

 livered in the evening of the day on 

 which the cattle show was held, and im- 

 mediately after the dinner, the attendance, 

 which amounted in all to about two hun- 

 dred, comprised a very large proportion of 

 the members of the society and the lead- 

 ing farmers of the district. Trie lecture 

 was illustrated by the use of tabular dia- 

 grams. The chair was again taken by C. 

 Gurney, Esq. 



Mr. Nesbit then came forward, and 

 said : 



# # # # # 



Allow me in the first instance to point 

 out- to you what I have termed " the ap- 

 plication of science to agriculture," Ag- 

 riculture, as an art, has existed' time im- 

 memorial. Our fathers and our grandfa- 

 thers and our great grandfathers, and all 

 c*ur ancestors before them, ploughed the 

 land and harrowed the land and tilled the 

 land ; the}' obtained crops and realized 

 certain results from certain operations — in 

 our country one way, in another country 

 in another way. But the facts of their 

 art, however numerous and important, had 

 never been collected — had never been 

 strung, as it were, together; they were 

 like the beads of a necklace, each unim- 

 portant by itself, but when strung together 

 forming an important whole. Now the 

 application of science to agriculture at the 

 present time is to collect the facts of ag- 

 riculture, facts with which you have be- 

 come perfectly familiar in your own expe- 

 rience, and to show why certain causes 

 produce certain effects ; and I believe I 

 shall be able to point out to you something 

 to-night which will enable you to trace 

 some of the facts with which you are your- 

 selves acquainted, to certain simple and 

 definite causes. The first point to which 

 I shall direct your attention is the nature 



of soils, because I think that before we 

 commence an}' investigation into the na- 

 ture of plants we should know something 

 about the character of the soils in which 

 they grow. Viewing our planet as a 

 whole, we may regard it as consisting of 

 earth, or solid matter;, water, or liquid 

 matter; and air, or gaseous matter. These 

 three kinds of matter are quite capable of 

 changing their form. The solid may be- 

 come a liquid or a gas, the gas a«liquid or 

 a solid ; and a liquid may become either 

 the one or the other. The particular mode 

 in which any of these forms of matter is 

 presented to us depends upon heat; so 

 that, you see, the old myth of the ancient 

 philosophers, that fire, 'air, earth, and wa- 

 ter are the four elements, is not in reality 

 so very far wrong. Taking a broad and 

 general view, it may be affirmed that the 

 solid matter, the liquid matter, and the 

 gaseous matter, aided by the light and the 

 heat of the sun which acts upon all these, 

 are the great elements upon which the ani- 

 mal and the vegetable existence of the 

 whole world depends. Now in this coun- 

 ty^ (Cornwall) we are blessed with a very 

 large amount of a certain rock called gra- 

 nite, which is regarded by geologists as the 

 primitive rock of the world, containing 

 within itself the material from which most 

 of the other rocks have been derived by 

 action of some kind or other upon its sur- 

 face. This granite, supposed to be the 

 primeval rock, has been subjected to the 

 operation of certain causes. Now granite 

 rock consists of certain substances which 

 are subject to the action of the air.— 

 Without mentioning at the present mo- 

 ment those properties of the air which act 

 upon granite, let me point out to you that 

 one of the chief ingredients in granite is 

 feldspar, which is found in all the granite 

 in Cornwall. This contains 65 per cent, 

 of a substance called silica, which you 

 know very well under the name of sand. 

 I am not speaking now of the shell-sand 

 of the coast, but of the hard, gritty, sili- 

 cious sand. It contains 18 per cent, of a 

 substance called alumina, which is the 

 base of clay; a pure alumina is. in fact, a 

 pure argillaceous matter. It also contains 

 a substance called potash, to the extent of 

 about 16 per cent. Now nothing at first 

 sight appears more indestructible than gra- 

 nite rock. But there is abundant evidence 

 that granite is very destructible, especially 



